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A four-legged snake from the Early Cretaceous of Gondwana

机译：冈瓦纳早期白垩纪的四足蛇

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摘要

Snakes are a remarkably diverse and successful group today, but their evolutionary origins are obscure. The discovery of snakes with two legs has shed light on the transition from lizards to snakes, but no snake has been described with four limbs, and the ecology of early snakes is poorly known. We describe a four-limbed snake from the Early Cretaceous (Aptian) Crato Formation of Brazil. The snake has a serpentiform body plan with an elongate trunk, short tail, and large ventral scales suggesting characteristic serpentine locomotion, yet retains small prehensile limbs. Skull and body proportions as well as reduced neural spines indicate fossorial adaptation, suggesting that snakes evolved from burrowing rather than marine ancestors. Hooked teeth, an intramandibular joint, a flexible spine capable of constricting prey, and the presence of vertebrate remains in the guts indicate that this species preyed on vertebrates and that snakes made the transition to carnivory early in their history. The structure of the limbs suggests that they were adapted for grasping, either to seize prey or as claspers during mating. Together with a diverse fauna of basal snakes from the Cretaceous of South America, Africa, and India, this snake suggests that crown Serpentes originated in Gondwana.
机译：如今，蛇是一个非常多样化和成功的群体，但是它们的进化起源却晦涩难懂。有两条腿的蛇的发现为从蜥蜴到蛇的过渡提供了线索，但是没有描述四肢的蛇，早期蛇的生态学还鲜为人知。我们描述了巴西白垩纪（Aptian）克拉托组的四足蛇。这条蛇的身体呈蛇形，尾巴细长，尾巴短，腹侧鳞片大，表明蛇形运动自如，但保留了小巧的四肢。头骨和身体的比例以及神经棘的减少表明骨骼适应性变化，这表明蛇是从洞穴而不是海洋祖先进化而来的。钩状的牙齿，下颌内的关节，能够约束猎物的柔软脊柱以及内脏中仍存有脊椎动物，这表明该物种以脊椎动物为食，而蛇则在其历史的早期过渡为食肉动物。四肢的结构表明它们适合抓握，既可以抓住猎物也可以在交配时拍手。与来自南美白垩纪，非洲和印度的多种基础蛇类动物一起，这条蛇表明冠蛇形蛇起源于冈瓦纳。

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  • 来源
    《Science》 |2015年第6246期|416-419|共4页
  • 作者

    Martill David M.; Tischlinger Helmut; Longrich Nicholas R.;

  • 作者单位

    Univ Portsmouth, Sch Earth & Environm Sci, Portsmouth PO1 3QL, Hants, England;

    Univ Bath, Dept Biol & Biochem, Bath BA2 7AY, Avon, England|Univ Bath, Milner Ctr Evolut, Bath BA2 7AY, Avon, England;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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  • 正文语种 eng
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